A quality air charter provider should be able to have you in the air within two hours of receiving a call for a pop-up, or last-minute, domestic flight. [See “Taking Off in a Hurry”] But what if you need to alter the passenger manifest or amend your destination shortly before takeoff? How flexible can your charter provider be regarding such changes?

Operators and brokers typically answer that question with can-do bravado. “This is what we do day in and day out,” said Paul Class, a senior vice president at TWC Aviation in Van Nuys, California. “Clients change itineraries, destinations and passenger counts all the time.” True, but ­charter operations are highly regulated, not only in terms of crew duty times but with regard to airport ­standards, weather minimums, crew training, maintenance and many other factors. This helps account for charter’s enviable safety record, but it can limit operators’ ability to make last-minute changes.

Not surprisingly, the scale of the change in your plans will largely determine your charter company’s ability to meet the request. If you’re scheduled to fly into New Jersey’s Teterboro Airport and decide an hour before takeoff that you instead want to arrive at New York’s Westchester County Airport, “we can probably make this happen without much hassle since the change is small,” said Tosh Desai, scheduling manager at Fair Wind Air Charter in Stuart, Florida. “However, if the same client asks to change the arrival airport to Toronto, and wants a larger jet than planned for, we have to look at availability of a larger jet, crew and duty-time issues, customs operating hours in Toronto and other logistical concerns.”

Here are tips that could make life easier should you need to alter your plans within hours of a scheduled flight:

Select your provider with an eye toward change. If you anticipate the possibility of last-minute modifications, make flexibility in this area a criterion for selecting your charter company. Ask the operator or broker about experience handling itinerary and manifest changes, and ensure that the provider has sufficient resources in terms of lift and logistical support to accommodate your needs. Ask about cancellation fees and waivers that would apply should alteration of plans become necessary.

Anticipate specific changes and communicate your needs. As soon as you envision the possibility of changes, discuss them with your charter provider. The operator can then alert the crew to be prepared to respond and perhaps to have a Plan B in place. “If you may need another size jet, we can sometimes place one on hold for you for 24 hours or until someone else wants to book it,” said Tom Bax, president of Sentient Jet Charter in Weymouth, Massachusetts. Gather identification documentation for anyone you think might be added to any manifest, so you can quickly provide the information to the charter company and any relevant government agencies should the need arise.

Allow time for destination changes. Even a change to a nearby airport sets a flight-planning department scrambling to check runway data, FBO services, hours of operation and other considerations. Planners may need to obtain landing and departing slots for major airports and airports with seasonal slot programs, and these slots may not be readily available. The planners will have to determine whether the changes will cause conflicts with the 14-hour duty-day limits for Part 135 pilots. A change in destination may also dictate a change in aircraft, if the category you originally planned to use is mismatched with the new mission.

Anticipate red tape on international flights. On international charters, visa and other regulatory requirements affect the ability to change destinations or manifests. If you decide you want to fly to mainland China instead of Hong Kong or add a colleague to your party, you can obtain a visa from a Chinese consulate in one working day. (This change may also require you to find a new charter operator, as only a handful operate into or out of mainland China.) If your change of plans involves Russia, keep in mind that a visa turnaround time of three to four days is considered expeditious. U.S. citizens flying into or out of their own homeland must have their names submitted to the Bureau of Customs and Border Protection at least 60 minutes before aircraft departure, so you may not be able to offer a lift home to the old friend you run into overseas.

Understand the consequences of changing the passenger manifest. If you’ve chartered a Hawker 400XP for your group of five and then decide you want to bring along three more associates, you may need a larger aircraft. On the other hand, if half your group contracts the flu the day before departure, a smaller, less expensive jet may be able to fulfill your mission.

Upgrading or downgrading your lift, particularly during peak demand periods, is the biggest challenge of last-minute charter changes, however. And even if the jet you’ve already booked offers sufficient seating for additional passengers, changes to your plans may be necessary. Added passengers may limit the fuel onboard, turning a direct flight into a one-hopper, and adding to your time en route.

Whenever you’re changing aircraft, be aware of the terms of your charter agreement, as hefty cancellation fees may kick in 24, 48 or 72 hours before the flight. (Some of all of these fees may be waived if you’re moving up to a bigger aircraft through the same operator.) Cancellation of empty-leg or discounted one-way charter flights may be subject to 100 percent forfeiture of the cost.